Dockboards are utilized in conjunction with a loading dock to span the gap between the dock and the bed of a truck parked in front of the dock, so that material handling equipment, such as a forklift truck, can travel between the dock and the truck bed.
One common form of dockboard is mounted in a pit or recess in the upper surface of the dock. A dockboard of this type, as disclosed in U.S. Pat. No. 4,068,338, includes a ramp or deck plate which is hinged at its rear edge to the dock and is movable between a generally horizontal storage position, where it is flush with the upper surface of the dock, to an upwardly inclined position. A lip is hinged to the forward edge of the ramp and can be pivoted between a downwardly hanging pendant position to an extended position where it forms an extension to the ramp and contacts the bed of the truck.
When the lip is extended and rests on a truck bed, the under surface of the ramp is exposed to the atmosphere. Under these conditions in a cold storage warehouse, the warm ambient air will contact the under surface of the ramp, while the upper surface of the ramp is exposed to the cool air of the warehouse, resulting in condensation on the under surface of the ramp and corrosion of the ramp and the working components of the dockboard.
Conversely, in extreme cold weather conditions, the under side of the ramp will be exposed to the cold ambient air, while the upper surface of the ramp will be exposed to the warmer air of the warehouse. Under these conditions substantial heat loss can occur through the pit area.
Also, and perhaps more importantly, hot or cold air is able to flow into the pit under the dockboard and up around the sides directly into the building, particularly in the case of a step type pit.